The Influence of Nd and Sm on the Structure and Properties of Sol-Gel-Derived TiO2 Powders

TiO2 nanopowders modified by Nd and Sm were prepared using the sol-gel technique. It was found by XRD analysis that the samples containing Sm are amorphous up to 300 °C, while those with Nd preserve a mixed organic-inorganic amorphous structure at higher temperatures (400 °C). The TiO2 (rutile) was not detected up to 700 °C in the presence of both modified oxides. TiO2 (anatase) crystals found at about 400 °C in the Sm-modified sample exhibited an average crystallite size of about 25–30 nm, while doping with Nd resulted in particles of a lower size—5–10 nm. It was established by DTA that organic decomposition is accompanied by significant weight loss occurring in the temperature range 240–350 °C. Photocatalytic tests showed that the samples heated at 500 °C possess photocatalytic activity under UV irradiation toward Malachite green organic dye. Selected compositions exhibited good antimicrobial activity against E. coli K12 and B. subtilis.

Visible Light Driven Photocatalytic Decolorization and Disinfection of Water Employing Reduced TiO2 Nanopowders

Defect-engineering of TiO2 can have a major impact on its photocatalytic properties for the degradation of persisting and non-biodegradable pollutants. Herein, a series of intrinsic and extrinsic defects are induced by post annealing of crystalline TiO2 under different reducing atmospheres. A detailed optoelectronic characterization sheds light on the key characteristics of the defect-engineered TiO2 nanopowders that are linked to the photocatalytic performance of the prepared photocatalysts. The photodegradation of a model dye, malachite green, as well as the inactivation of bacterial endospores of the Geobacillus stearothermophilus species were studied in the presence of the developed catalysts under visible light illumination. Our results indicate that a combination of certain defects is necessary for the improvement of the photocatalytic process for water purification and disinfection under visible light.

The influence of TiO2 and N-TiO2 nanopowders in natural leather finishing for heritage or modern binding

The methods for processing raw hides over time, have been numerous: smoke, fat, fermented milk, egg, volcanic soils, plants (shells, fruits, leaves) and so on. The books binding with leather has its origins in the Orient and are known various types of goatskin and calfskin, tanned with sumac finished marbled (sapphire), in black (Moroccan), by floating and dyeing in various colors (Cordoba leathers). Preoccupations regarding the assurance of optimal characteristics for the binding leathers, respectively the durability of the leathers for the restoration of the patrimony objects or of the modern binding were of the most topicality in the last decades, abroad and also in our country. The paper describes the finishing of vegetable and alum tanned leather samples that have been functionalized with titanium dioxide (TiO2) or nitrogen-doped titanium dioxide (N-TiO2) nanopowders, in different concentrations. To simulate soiling in real conditions, four types of soiling agents were applied: tea, coffee, beetroot extract and pen paste. The samples were exposed to irradiation in a photoreactor with various light sources for up to 192 hours. The evaluation of the photocatalytic degradation was performed by the CIELab technique.

Antibacterial Compound based on Silicone Rubber and ZnO and TiO2 Nanoparticles for the Food and Pharmaceutic Industries. Part II - Biological and Morphological Characterization

The aim of this paper is the biological and morphological characterization of an antibacterial compound based on silicone rubber (Elastosil R701/70-OH), reinforced with ZnO and TiO2 nanopowders (with antibacterial, antifungal and antimicrobial properties), charged (chalk), crosslinked with peroxide (dicumyl peroxide - powder 40% with calcium carbonate and silica, specific to the food, pharmaceutical, but also medical field). ZnO and TiO2 nanopowders, by their homogeneous dispersion in the mass of the compound, have a determined role on its antibacterial and antimicrobial sterilization properties. The mixture of antibacterial compound based on silicone rubber was made on a laboratory roller, provided with cooling, in the form of a sheet (maximum thickness 5 mm), in strict compliance with the technological recipe and the established mode of operation. Subsequently, the mixture is processed into forming molds at predetermined parameters by determining the vulcanization time using the Monsanto rheometer (to determine the optimum temperature and vulcanization times), but also the biological and morphological characterization, according to current standards in specific food and pharmaceutical environments.